That is a great gesture on the part of either the GPAA or the show hosts. If you are enrolled in VA healthcare, then you will have a picture ID card for that. That should do, it has for me when different businesses have offered something for vets. As a sidebar, VA healthcare also meets the requirements of Obamacare.
I don't know if the pre-registration free entry pass is still going on or not, but if so it should be on the show page. You just don't get the vial if you are in the first batch in the door.
As Paul noted, THANK YOU
**EDIT**---Just got an email for the Portland show--If I decide to go, (we might have a booth for the chapter, but that is iffy right now) I would have to get in with the vet thing too (it is also listed for there) as I couldn't afford to drive up there and pay the other associated fees and charges besides the show entry tariff of $10.00 to get in. Did not see anything of the free pre-registration but there is a half off for pre-registration at the Portland show.